Excessive crop residue or trash left on a field after a crop is harvested can hamper field operations. Often it is required to turn the residue under the soil with a disc or plow in order to conduct field operations. It is also common to harrow the field to spread the crop residue evenly to facilitate field operations. It has also been known to burn the residue off the field or chop the residue with a rotary mower. Such discing, harrowing, and chopping is costly, and burning is harmful to the environment, and also wasteful of plant nutrients present in the crop residue.
Recently as well, minimum or zero tillage farming practices have become popular to preserve moisture and reduce erosion. In such practices no tillage is done to turn crop residues under the soil, and residue management has become increasingly important in agriculture.
Seeding implements generally include a ground engaging furrow opener mounted on the bottom end of a shank extending down from a seeding implement frame. Where the furrow opener is a knife or hoe type opener, the furrow opener is pulled through the soil to create a furrow, and crop residue flows around the shank. Longer crop residue pieces such as straws and vines are problematic. Most of these straws will flow to one side of the shank or the other, but some will contact the shank at a midpoint such that, as the shank moves forward, one end moves backward on one side of the shank and the other end moves backward on the other side of the shank and the straw then hangs on the shank with a portion dragging along on each side of the shank. These dragging pieces tend to pick up more pieces such that a sizable clump of residue can grow on the shank, increasing draft and interfering with penetration of the furrow opener into the ground.
While often these clumps will fall off to one side of the shank or the other, sometimes the clumps build up to the point where they start to mix with and push soil and the seeder plugs and must be raised to clear the residue and soil, and sometimes the mixed clumps and soil must be manually removed.
When the clumps do fall off on either side of the shank, the clumps tend to fall back onto the furrow directly behind the shank. Soil engaged by the furrow opener at the bottom of the shank flows around the sides of the shank and falls back behind the shank and into the furrow. Further, the area directly behind the shank is clear of crop residue and thus creates more or less a trench in the residue. When a clump moves off the side of the shank the moving soil appears to carry the clump around and behind the shank, and the standing residue adjacent to the sides of the trench tips the clump into the cleared area. In any event the clumps fall onto the furrow and interfere with the emergence of plants growing from seeds planted in the furrow.
Clumps that do not fall into the furrow are also problematic as they lay on the ground and form bumps such that the field becomes rough for travel in later passes over the field, and as wheels pass over the bumps, depth control of ground engaging tools is adversely affected.
In addition to seeding, other ground engaging tools such as cultivator shovels are used in cultivation of agricultural fields, and are subject as well to residue build up on shanks mounting the tools to the implement frame.
Where the furrow opener is a rotating disc, the residue does not build up on the shank because the disc rolls over heavy residue, interfering with disc penetration and seed placement.
For these reasons various trash clearing mechanisms have been developed to clear residue off a path along the ground ahead of the furrow opener, for example such as that disclosed in U.S. Pat. Nos. 5,640,914 to Rawson and 5,477,792 to Bassett et al. Such mechanisms provide one or more spoked wheels or discs running at an angle ahead of the furrow opener and kicking the residue to the side. U.S. Pat. No. 6,345,671 to Siemens et al. discloses a fingered wheel located adjacent to the furrow opener that pins crop residue to the ground surface and prevents the residue from lodging on the shank.
Patent Cooperation Treaty Application WO2009127066 of Beaujot discloses a system where a residue clearing member periodically moves laterally across the front face of the shank to move clumps of crop residue laterally and off the shank on one side or the other thereof. It is contemplated that these clumps may also fall back on top of the furrow as described above, or in any event leave the soil surface bumpy.